An angle consists of a vertex and two arms and is measured using a protractor. To measure an angle, place a protractor over the angle so that the vertex is covered and one arm aligns with the 0 degree mark. Read the measurement where the other arm intersects the protractor. Angles are measured in degrees.

1. Geometry Investigating Angles

2. Angles An angle consists of a vertex and two arms. This angle is named XYZ or ZYX X Y Z vertex angle arm arm

3. Measuring Angles

4. Angles Angles are measured using a protractor. The unit of measurement is a degree. Vertex

5. Angles To measure an angle, place a protractor over the angle so that X Y Z

6. Angles To measure an angle, place a protractor over the angle so that The vertex of the angle is covered by the vertex of the protractor X Y Z

7. Angles To measure an angle, place a protractor over the angle so that One of the arms of the angle aligns with the base (0°) of the protractor X Y Z

8. Angles Begin at the 0° mark Begin reading around the protractor until you reach the other arm of the angle. X Y Z

9. Angles You can read the degree measure of the angle directly off the protractor. X Y Z

10. Angles Since the initial zero degree measure was on the inside, then XYZ = 50° . X Y Z

11. Angles We can measure this angle. R T S

12. Angles We can measure this angle. R T S

13. Angles We can measure this angle. We write… RST = 105° R T S

14. Angles Estimate the measure of LMN. N M L

15. Angles Measure LMN. N M L 57 ° LMN = 57°.

16. Angles What is the measure of the angle shown? D E F 128 ° DEF = 128 °

17. Angles What is the measure of the angle shown? A C B 106 ° ACB = 106 °

18. Angles What are the measures of the angles shown? G J H 127 ° KJG = 127 ° HJG = 53 ° K 53 °

19. Practice with Measuring Angles Try this website… Random Angle Measurement